kizzx2 / sbe-python Goto Github PK

Hi guys, just wanted to run this by here. Would the body of the second if statement ever be hit? Doesn't seem like it would. Is this a bug?

            if isinstance(f, Group):
                assert cursor.val >= header.value['blockLength']
                if cursor.val < header.value['blockLength']:
                    format_str_parts.append(str(header.value['blockLength'] - cursor.val) + 'x')

Link to line of the code

Hi,
I like the library, ease of use is great. We have a common constant field defined across all templates in my project that can be used for semantic grouping however the DecodedMessage value dict doesn't not contain representation of the constant. I'd like to use this library in a project that uses some SBE constant fields however I can see in the code that constants are specifically ignored.
Can the constant value be added to the values dict instead of being ignored?
Thanks,
Mike

Hello

I think it does not support referencing custom data type. The xml i fail to parse is here:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<sbe:messageSchema xmlns:sbe="http://fixprotocol.io/2016/sbe"
                   package="proper.market.api"
                   id="1"
                   version="1"
                   semanticVersion="1.0"
                   description="for market data transfer"
                   byteOrder="littleEndian">
    <types>
        <composite name="messageHeader" description="Message identifiers and length of message root">
            <type name="blockLength" primitiveType="uint16"/>
            <type name="templateId" primitiveType="uint16"/>
            <type name="schemaId" primitiveType="uint16"/>
            <type name="version" primitiveType="uint16"/>
        </composite>

        <enum name="innerthing" encodingType="uint8" description="trading exchange">
            <validValue name="value0">0</validValue>
            <validValue name="value1">1</validValue>
        </enum>
        <composite name="something">
            <ref name="innerthing" type="innerthing"/>
        </composite>
    </types>
    <sbe:message name="someMsg" id="1">
        <field name="something" id="1" type="something"/>
    </sbe:message>

</sbe:messageSchema>

When parsing a schema with message tags that don't specify the blockLength attribute, I get this error:

...
...\lib\site-packages\sbe\__init__.py", line 1088, in _parse_schema      
    blockLength=int(attrs['blockLength']),
KeyError: 'blockLength'

It looks like the parser depends on this attribute being there, however SBE specifies that blockLength is optional:

<xs:attribute name="blockLength" type="xs:nonNegativeInteger" use="optional">

when decoded data_type: Fixed Array Fields（array-int），result is single value，not array。

Would be great to have an example of how to encode the message. There is a snippet in the documentation, but I'm not sure I understand what obj is:

import sbe

with open('./your-schema.xml', 'r') as f:
  schema = sbe.Schema.parse(f)

# message_id from the schema you want to encode
message_id = 3

# Encode from Python dict in one-line
schema.encode(schema.messages[3], obj)

# You can supply your header values as a dict
schema.encode(schema.messages[3], obj, headers)

I've noticed that after parsing a schema, the description field of instances of several classes remains None. I haven't exhaustively tested this, but at least for message and field tags the description attribute does not get propagated to the corresponding objects.